Specifications

CD-i FAQ 2000 Edition Revised February 21, 2001
Latest version and more CD-i info: http://www.icdia.org
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5. Disc types
5.1 What is a CD-i disc?
A CD-i disc is a type of CD with audio, video and program content that can be played on a CD-i
player. A CD may be called a CD-i disc only when it fully conforms to the CD-i Full Functional
Specification, as laid down in the Green Book. When a CD-i disc does not fully conform to this
specification (even if it can be played on a CD-i player, such as a Photo-CD or a Video-CD), it is
not a CD-i disc. You can recognize a CD-i disc by its official logo that should be printed on the
discs cover and on the disc itself. For more information about the CD-i system, the logo and the
Green Book, refer to section 1 of this FAQ: The CD-i system.
5.2 What is CD-i Ready?
CD-i Ready is a special kind of CD-i disc. Following the rules from the Green Book, a CD-i disc
may contain CD-Audio tracks. These should be placed after the CD-i track which is always track
1. However, on some older CD-Audio players, this CD-i track would be played back resulting in
possible damage to equipment or speakers. To prevent this, the CD-i Ready format was defined.
On a CD-i Ready disc, the CD-i program data (including all of its audio and video information) is
stored in the pause sectors preceeding track 1. Usually, pause sectors preceeding track 1 are
skipped by most CD-Audio players, but they can be read fine on a CD-i player. This allowed for a
greater compatibility of CD-Audio discs which contained extra information when played on a CD-i
player. In essence, a CD-i Ready disc is not a true CD-i disc, since it does not follow the rules of
the Green Book for placing CD-Audio data, but they can be read correctly by all CD-i players ever
produced.
CD-i Ready discs are usually music CDs (you can recognize these CDs by the indication CD-i
Ready or CD-i Music in the upper left corner of the disc packaging), but they may also be other
kinds of discs. For example, some games (most notably the games produced by SPC Group/The
Vision Factory) are known to be in the CD-i Ready format. CD-i players equiped with the second
generation player shell (refer to Comparison table of all Philips CD-i players at www.icdia.org)
may optionally play the audio-tracks of a CD-i Ready disc using the standard CD-Audio screen.
5.3 What is CD-Digital Audio or CD-DA?
Compact Disc Digital Audio is the official name of the original music CD. It was defined by Philips
and Sony in the early 80s and its specifications were laid down in the Red Book. All CD discs and
CD players should be in accordance with this specification to allow the bearing of the Compact
Disc Digital Audio logo. This specification assures that every CD-Audio disc can be played in
every CD-Audio player where-ever in the world.
The Green Book defines that any CD-i player should be able to play back CD-Digital Audio discs.
For this, a CD-i player pops up a player shell when a CD-Audio disc is loaded in the player. This
player shell allows for the direct selection of tracks, for programming Favourite Track Selections,
for standard search options, etc. It's up to each manufacturer to decide what this player shell will
look like and what features are offered, as long as all content of a CD-Audio disc can be played
back on a CD-i player.
Look for the special note about CD-Extra (CD-Plus or Enhanced CD) in question 5.18.
5.4 What is CD+Graphics?
CD+Graphics or CD+G is an extension to the Red Book, defined by Philips and JVC. CD+G
allows for the storage of simple graphics in the subcode channels of each sector on a CD-Audio
disc. Each sector has 8 subcode channels combining 384 bits, resulting in 75 (sectors per